1. Field
The present disclosure relates to a device and method of wireless communication for vehicle-to-vehicle (V2V) communication in a vehicle. More specifically, embodiments in the present disclosure relate to a device and method of wireless V2V communication with switching among a plurality of radio transmission configurations depending on assumed a positional relationship between a signal transmitting vehicle and a signal receiving vehicle, and signal environmental factors, such as potential obstacles and geographical surroundings.
2. Description of the Related Art
Frequently, in vehicle-to-vehicle and vehicle-to-infrastructure (V-to-X) communication, communication failure may occur with high possibility mainly because of weak radio propagation when obstacles are located on a communication path. Radio propagation degradation has been believed to be relatively large when any large obstacles are located on a communication path, thus an increase of radio output intensity and/or replacement of a radio frequency to that of lower frequency channel with low directionality have been considered as appropriate implementation. There have been several methods of switching between a plurality of radio frequency bands proposed that enable lower frequency channels with low directionality. For example, Japanese patent publications JP 2005-204218 and JP 2008-236409 teach that it is effective to switch between two frequency bands for transmission with other vehicles in the vicinity, considering information regarding surrounding vehicle information and surrounding buildings available from map database. Another Japanese patent publication, JP 2009-231996, further teaches switching between two frequency bands depending on visual information available by capturing images of surrounding objects that possibly become obstacles.
However, too strong radio propagation by large radio output intensity or low radio frequency is likely to interfere to communications between neighboring vehicles (i.e. in freeways or urban intersections) or other communications with adjacent frequencies. It is especially true when the vehicle is approaching to an area where many vehicles are approaching and leaving, such as an intersection, an end of a slope where deceleration tends to occur, freeway exits and junctions, etc. In order to avoid radio interference to communications with neighboring vehicles in such a congested area, the usage of the increase of radio output intensity and/or replacement of the radio frequency to that of lower frequency channel is preferably limited, to reduce unnecessary communications of other vehicles in the vicinity that are not the designated counterpart of the vehicle's communication.
Accordingly, there is a need to provide a method and device that allows a vehicle to wirelessly communicate with other vehicles with effective frequency and intensity switching of its radio signals while reducing redundant communication due to lower frequency and high intensity signals and resulting in minimizing radio signal interference to a traffic congested area.